Air compressing apparatus



Oct. 1, 1968 R. c. MARSHALL AIR COMPRESSING APPARATUS 3 Sheets-Sheet 1 Filed Sept. 27, 1965 INVENTOR. RIC/MRO C MARS/ flu Mn h/lfzer Oct. 1, 1968 R. c. MARSHALL AIR COMPRESSING APPARATUS 5 Sheets-Sheet 2 Filed Sept. 27, 1965 I NVEN'TOK u m M m M wm c. m 0 m m m R Oct. 1, 1968 R. c. H L I 3,403,845

AIR COMPRESS ING APPARATUS Filed Sept. 27, 1965 6 Sheets-Sheet 3 41' 43 35 42- Y i 40 I I as 5 i 6? 72' 6' 62. i I :n \E' i as 7s- 73 E 5 I 55 i 33 izs 24 1 INVENTOR. RICHARD C. MARS/M11 United States Patent 3,403,845 AIR COMPRESSING APPARATUS Richard C. Marshall, 917 W. 43rd St., Kansas City, Mo. 64111 Filed Sept. 27, 1965, Ser. No. 490,281 9 Claims. (Cl. 230190) ABSTRACT OF THE DISCLOSURE An apparatus for compressing gaseous fluid and including a reciprocating compressor and a receiver or tank connected with the discharge of the compressor for receiving the compressed gaseous fluid. The compressor including a cylinder with a reciprocating piston therein with one end of the cylinder being a discharge opening controlled by a discharge valve, said cylinder having inlet ports adjacent the other end thereof with said inlet ports having a total area as great as the cross sectional area of the cylinder bore. The piston has a passage therethrough controlled by an intake valve that is of large size but with the periphery spaced from the cylinder so that when the inlet valve is moved to an open position the passage area between the valve and cylinder is as great as the cross sectional area of the flow opening through the piston. The structure is such that the inlet ports, valve openings and flow passages are all of a size to permit substantially unrestricted gaseous fluid movement from the inlet through the compressor to the delivery pipe to the tank providing a compressor wherein the output varies substantially directly with the r.p.m. of the compressor.

Heretofore, in air compressors and the like, it has been recognized they should be operated at a recommended maximum speed, and operation above that maximum would reduce the compressors efliciency and positive displacement reciprocating air compressors capable of operating at various speeds at substantially the same efficiency, that is, with an output proportional to the relative speeds, have not been available.

The principal objects of the present invention are to provide a fluid compressor system including a reciprocating compressor that may be operated at various speeds and provide an output proportional to the respective speed; to provide a compressor system including a reciprocating compressor, a tank and flow passages wherein gaseous fluid compressed by the compressor has substantially unrestricted movement from intake ports to the tank; to provide a compressor system wherein the operation provides substantially maximum fluid moving value of the piston stroke; to provide a fluid compressing system wherein the compressor is of a structure that permits easy accessibility to the valve elements; and to provide a compressor system that is economical to manufacture, easily maintained and that provides substantially positive displacement whereby the output varies with the speed of operation.

Other objects and advantages of this invention will become apparent .from the following description taken in connection with the accompanying drawings wherein are set forth by way of illustration and example certain embodiments of this invention.

FIG. 1 is a side elevation of a compressor structure embodying the features of the present invention.

FIG. 2 is a vertical sectional view through a compressor connected in a compression system including a flow passage and tank.

FIG. 3 is a transverse sectional view through the compressor taken on the line 3-3, FIG. 2.

FIG. 4 is a transverse sectional view through the compressor cylinder head taken on the line 4-4, FIG. 2.

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FIG. 5 is a transverse sectional view through the cylinder and piston taken on the line 5-5, FIG. 2.

FIG. 6 is a transverse sectional view through the cylinder and intake ports taken on the line 66, FIG. 2.

FIG. 7 is an enlarged fragmentary view of the compressor showing the cylinder, piston and valves.

Referring more in detail to the drawings:

The reference numeral 1 generally designates a gaseous fluid compressing system which includes a compressor 2, a receiver 3, and a flow passage 4, providing flow communication between the compressor discharge 5 and the receiver or tank 3. The compressor 2 includes a base 6 having a crank-case or housing 7 with suitable bearing structures 8 rotatably mounting a crankshaft 9 with a crankpin bearing 10 rotatably connected to one end of a connecting rod 11. In the structure illustrated, the compressor is of the vertical type; however, it is to be understood it also could be horizontal or other conventional positioning without change of functin or operation. Also, any conventional connection between the crank and piston 12 may be utilized.

In the structure illustrated, the crankcase has an opening 13 communicating with the interior 14 of a crosshead guide 15 suitably secured to the crankcase. The various parts may be cast or formed by any conventional means; however, in the structure illustrated, parts are fabricated wherein the crosshead guide 15 includes a tubular barrel 16 with a flange 17 secured to the lower end thereof as by welding and the crankcase has a mounting ring 18 secured thereto as by welding and the flange 17 of the crosshead guide is secured relative to the crankcase by suitable fastening devices such as screws 19 screwed into threaded bores 20 in the ring 18.

A crosshead member 21 is reciprocable in the bore of the tubular guide sleeve or barrel 16 and has depending cars 22 mounting a piston pin 23 forming a pivotal connection with the upper end of the connecting rod 11. The piston 12 and the crosshead 21 are operatively connected by a cylindrical rod 24 that extends through a bore 25 of a stuffing box member 26 having suitable packing 27 surrounding the guide rod 24 to provide an effective seal around the guide rod 24 at the upper end of the crosshead guide. The stufling box member 26 is supported at the upper end of the tubular barrel 16 and is suitably secured thereto as by welding wherein the structure provides an outwardly extending annular flange 28.

A cylinder 29 has a bore 30 in which the piston 12 reciprocates. In the structure illustrated, the cylinder Wall 31 is secured to a bottom flange 32 as by welding, and the cylinder mounted on the crosshead guide in axial alignment therewith by means of suitable fastening devices such as bolts 33 that extend through the flanges 28 and 32. The other end or discharge end of the cylinder is provided with an annular flange member 34 on which is mounted a cylinder head 35. The flange member 34 is sleeved on the cylinder wall 31 and is secured thereto as by welding. The discharge end of the cylinder wall 31 is preferably recessed below the upper surface 36 of the flange member 34 and said flange member is provided with a counterbore 37 which registers with the bore or flow passage 38 of the cylinder head that is greater in cross-sectional area than the cross-sectional area of the cylinder bore 30.

The discharge end of the cylinder wall 31 is beveled outwardly from the bore to provide a valve seat 39 on which a valve head 40 seats in closing the discharge end of the cylinder bore. The valve head 40 has a stem 41 reciprocably mounted in a bore 42 of a tubular guide or sleeve 43 supported in the cylinder head 35 by means of a plurality of circumferentially spaced webs 44 that are secured to the guide sleeve 43 and to the peripheral wall of the cylinder head. The webs 44 are relatively small whereby they do not materially reduce the cross-sectional area of the flow passage through the cylinder head.

A cylinder head cap 45 is removably secured on the cylinder head by suitable fastening devices such as screws 46 screwed into threaded bores 47 in the top flange 48 of the cylinder head. The cap has a neck 49 suitably connected to the flow passage member 4 leading to the tank or receiver 3. In the structure illustrated, the flow passage 4 consists of a tubular pipe 50 having a bore 51 only slightly smaller than the bore 30 of the cylinder 29. In the structure illustrated, the pipe member 50 is threadedly connected to the neck 49 as at 52. Also, the interior surface 53 of the cap is of suitable shape whereby it is spaced from the guide 43 and valve stem 41 so as to provide substantially unrestricted fluid movement thereby. The lower end of the guide 43 is substantially spaced above the valve head 40 and forms an upper limit of travel therefor. However, this provides a spacing between the periphery of the valve and the interior of the cylinder head so that the circular area therebetween is greater than the crosssectional area of the bore 30 of the cylinder. In operation, diflerential pressure will actuate the discharge valve whereby the valve head 40 moves to and from seated position. However, in the structure illustrated, a light conical coil spring 54 is interposed between the webs 44 and the valve head 40 to provide a very slight urging of the valve head to closed position.

The lower portion of the cylinder 29 is provided with intake ports 55 that have a total cross-sectional area substantially equal to the cross-section of the cylinder bore 30. The piston 12 is slidably mounted in the bore 36 and reciprocates therein whereby the upper end 56 of said piston moves at the compression end of its stroke to substantially the lower face 57 of the valve head 40, there being only slight clearance therebetween when the valve is in closed position and the piston at the upper end of its stroke. The length of the cylinder 29 and piston 12 is such that when the piston is reciprocated to the lower end of its stroke, the lower end 58 of the skirt thereof is above the intake ports 55.

The piston 12 has a head 59 with the skirt 60 extending therefrom toward the intake end of the cylinder. The periphery of the cylinder is provided with a plurality of spaced grooves 61 in which is mounted suitable piston rings 62 to engage the inner surface of the cylinder wall. A plurality of circumferentially spaced webs 63 are suitably secured to the skirt and extend inwardly therefrom with their inner ends secured as by welding to an upper reduced end 64 of the guide rod 24. The upper portion of the guide rod has an axial bore 65 extending therein with a bearing sleeve 66 mounted in said bore and opening at the piston end thereof. An intake valve 67 has a stem 68 reciprocable in the sleeve 66 with the head 69 of said valve provided with a peripheral portion 7 seating on a valve seat 71 at the discharge end of an intake bore 72 in the piston head. The bore 72 and the valve head 69 are as large as practical so as to offer substantially unrestricted movement of gaseous fluid from one side of the piston to the other. While the intake valve may operate from differential pressures acting thereon, it is preferred to have a very light spring biasing same to closed position. In the illustrated structure, the valve stem has an extension 73 with a head 74 spaced from the lower end of the sleeve 66. A spring 75 is interposed between the head 74 and a washer 77 engaging the sleeve 66 to bias said intake valve to closed position.

It is preferred, as illustrated in FIG. 1, that the cylinder head and cylinder both have a plurality of closely spaced cooling fins 78 thereon to facilitate dissipation of heat from the compressor. The receiver or tank 3 may be of any conventional structure and preferably would have a pressure gauge 79 connected thereto and a suitably controlled outlet 80 leading to a point of utilization of the compressed fluid. An example of the output of a compressor system is evident from a comparison wherein a single cylinder 2% inch bore, 2% inch stroke, compressor was connected to a 30-gallon tank with a compressor speed of 510 r.p.m., it required more than 16 minutes to deliver suflicient 'air to the tank to raise the pressure therein from zero to pounds. The same compressor operated at 950 r.p.m. delivered air to the tank to raise the pressure therein from zero to 150 pounds in approximately 9 minutes. Also, when the same size air compressor system was operated under ASME performance testing code No. PTC9-1954, wherein the compressor was operated at one speed at 545 r.p.m. and at another speed of 975 r.p.m., it was found that the air flow increase was 1.78 to 1 with an r.p.m. increase of 1.79 to 1. This shows that the output of air varies substantially directly with the r.p.m. of the compressor.

In operating a compressing system constructed and assembled as described, a suitable source of power is connected to the crankshaft to rotate same, reciprocating the piston 12 in the cylinder 29. As the piston is moved toward the intake end of the cylinder with the discharge valve in closed position, there is a reduction of pressure in the cylinder bore 30 between the intake and discharge valves. This causes a differential pressure to act on the intake valve 67, moving same to open position whereby air from the intake ports 55 enter the lower end of the cylinder and passes through the interior of the piston between the webs 63, through the bore 72, past the valve 67 into the upper end of the cylinder. When the piston reaches the lower end of its stroke, the pressure on each side of the valve head 69 equalizes, and the valve moves to closed position. Then, on the upstroke or compression stroke of the piston 12, air is compressed between the piston and the discharge valve and, when the pressure in the cylinder is such that a differential pressure acting on the discharge valve causes same to open, the air moves around the discharge valve head, through the cylinder head, past the webs 44 therein and through the passage 4 to the receiver or tank 3. When the piston has completed its upper or compression stroke, the differential pressure or pressure on each side of the discharge valve tends to equalize and the discharge valve moves to closed position as the piston 12 starts down on its next suction or intake portion of its stroke. With this arrangement, the air or gaseous fluid is compressed, and there is substantially unrestricted movement of the fluid from the intake ports of the receiver or tank.

It is to be understood what while I have illustrated and described one form of my invention, it is not to be limited to the specific form or arrangement of parts herein described and shown except insofar as such limitations are included in the claims.

I claim:

1. An air compressing apparatus comprising:

(a) a tank,

(b) a cylinder having a bore,

(c) a cylinder head closing one end of said cylinder bore,

(d) a piston extending into the other end of said cylinder bore and reciprocable therein,

(e) intake ports of a total area as great as the crosssectional area of said cylinder bore, said ports being at said other end of said cylinder,

(f) an intake valve in said piston opening for flow of air from the intake ports to the cylinder between the piston and cylinder head during movement of said piston away from said cylinder head,

(g) a discharge valve in said cylinder head of a size substantially that of the cross-section of the cylinder bore and opening in response to pressure in the cylinder,

(h) a flow passage from the cylinder head to the tank with a cross-sectional area for its length of a size whereby there is substantially unrestricted air movement from the compressor intake ports to the tank.

2. An air compressing apparatus as set forth in claim 1 wherein the inlet valve is movable to an open position in which the spacing between the inlet valve periphery and the cylinder is such that the passage area therebetween is as great as the cross-sectional area of flow opening through the piston.

3. An air compressing apparatus as set forth in claim 2 wherein said discharge valve is movable to an open position in which the spacing between the discharge valve periphery and the cylinder head is such that the passage area therebetween is as great as the cross-sectional area of the cylinder bore.

4. An air compressing apparatus comprising:

(a) a crankcase,

(b) a cylinder block extending from said crankcase and having a cylinder bore,

(c) a crank in said crankcase,

(d) a piston in said cylinder bore,

(e) a connection between said piston and said crank,

(f) a suction passage having an inlet and communicating with the interior of said cylinder block below said piston and of a size with a cross-sectional area as great as that of the cylinder bore,

(g) a hollow cylinder head connected to said cylinder block at the end spaced from the crankcase,

(h) a delivery pipe communicating with the interior of said cylinder head and having a cross-sectional area substantially as great as that of the bore of the cylinder,

(i) a discharge valve in said cylinder head,

(j) an inlet valve in the piston,

(k) said inlet valve and discharge valve each moving to open and closed position in response to pressure diiferential acting thereon, said valves, the suction passage and the discharge pipe all being of a size to permit substantially unrestricted air movement from the inlet through the delivery pipe.

5. A compressor as set forth in claim 4 wherein there is a discharge valve seat on the cylinder surrounding the cylinder bore at the discharge end thereof and the discharge valve seats on said seat to close said discharge end of the cylinder, said discharge valve having a periphery spaced from surrounding portions of the cylinder head whereby when the discharge valve is in open position said spacing defines an area as great as the cross sectional area of the cylinder bore.

6. A compressor as set forth in claim 5 wherein the discharge valve has a shank reciprocably supported in a guide member supported on webs in the hollow cylinder head with the guide means spaced from the discharge valve when in closed position and from the cylinder head for substantially unrestricted air flow therethrough when the discharge valve is in open position.

7. An air compressor as set forth in claim 6 wherein the piston is a hollow substantially cylindrical member with a valve seat at one end and the connection with the crank extending from the other end with Said piston having a large cross-sectional area passage therethrough and a valve closes upon the seat in the piston.

8. An air compressing apparatus comprising:

(a) a tank,

(b) a crankcase provided with an upwardly extending cylindrical crosshead guide,

(c) a cylinder block comprising a base secured to the crosshead guide,

((1) a crank in said crankcase,

(e) a crosshead operable thereby,

(f) a piston in said cylinder,

(g) a piston rod connection between said piston and said crosshead,

(h) a packing gland mounted upon the upper end of said guide and embracing said piston rod connection,

(i) a suction passage having an inlet and communicating with the interior of said cylinder block below said piston and of a size with a cross-sectional area as great as that of the cylinder,

(j) a hollow cylinder head connected to said cylinder block at the end spaced from the crankcase,

(k) a delivery pipe communicating with the interior of said cylinder head and having a cross-sectional area substantially as great as that of the bore of the cylinder,

(1) a discharge valve in said cylinder head,

(m) an inlet valve in the piston,

(11) said inlet valve and discharge valve each moving to open and closed position in response to pressure differential acting thereon, said valves, the suction passage and the discharge pipe all being of a size to permit substantially unrestricted air movement from the inlet through the delivery pipe to the tank.

9. An air compressor as set forth in claim 8 wherein the piston is a hollow substantially cylindrical member with a valve seat at one end and said piston rod connection extending from the other end, said piston rod being connected to the piston by a plurality of webs providing a large cross-sectional area passage therebetween and said inlet valve closes upon the seat in the piston and has a stern extending through and guided in an end of the piston rod, a resilient means in said piston rod acting on the valve stem to urge the inlet valve toward said valve seat in the piston.

References Cited UNITED STATES PATENTS 1,557,706 10/1925 Knox 230 1,590,766 6/1926 Lipman 230-190 1,938,218 12/1933 Dempsey 230190 2,017,975 10/1935 Kooyman 103-227 3,081,934 3/ 1963 Abernathy et al 230-24 1,467,503 9/1923 Rottel 230190 OTHER REFERENCES Pages 305 to 312 of textbook entitled Pumps (second edition, 1953), by Frank A. Kristal and F. A. Armett, published by McGraw-Hill Book Company, Inc., New York.

WILLIAM L. FREEH, Primary Examiner. 

